How important is an audio rack?

Regardless what some manufacturers say, all components create mechanical resonance. I have used some expensive and well-known footers and other tweaks to try to solve the problem. Some products made a slight difference. Others made no difference at all. I have no experience with commercially-made racks.

I have solved the problem very effectively -- and inexpensively. The solution is not particularly aesthetic but it is not offensive or obtrusive. I have my components on very heavy custom-made solid wood tables. The table tops are 3 inches thick. I bottom load all components using large Tupperware-styled containers filled to the brim with dry beach sand. This is an old remedy that works wonderfully in my system. The maker of my speakers who said this solution would not work for his speakers was surprised when I told him how well it does in fact work. I sold off all my footers and tweaks.

Yes, very effective. I use high quality Tupperware look-alike containers. They are robust enough to support my 32 kg. Marantz amplifier without any problem. As long as they are high quality and the sand is dry you should be fine. Make sure you shake the container as you fill it so that you will be able to load the maximum amount of sand in each container.